Offender:
structures\nature\trees\GenericTreeSmall.rcst

This oak tree has acacia leaves. Here is a replacement file changing the leaves to oak leaves

Edit: Forgot to include some key information
MC: 1.10.2
Forge: 2254
RC: 1.2.9.1-1.10.2

Upon further inspection, There is another tree oak tree that has birch leaves. I haventn't found the file for that one yet

Fixed in ddf9916. Let me know if there are others.